1. Field of the Invention
The disclosure relates generally to devices for real-time frequency correction, and more particularly, relates to devices for correcting the real-time frequency by two adjacent integers.
2. Description of the Related Art
A real-time clock, which is a counter for counting years, days, hours, minutes, and seconds, includes a quartz oscillator, a second counter, a minute counter, an hour counter, a day counter, and a year counter. The output frequency of the quartz oscillator is usually assumed to be 32768 Hz.
The second counter counts the output pulses of the quartz oscillator. When the counting of the second counter reaches 32768, a notification signal is outputted to the minute counter. When the counting of the minute counter reaches 60, the minute counter outputs a notification signal to the hour counter. When the counting of the hour counter reaches 24, the hour counter outputs a notification signal to the day counter. When the counting of the day counter reaches a predefined value, the day counter outputs a notification signal to the year counter.
The accuracy of the real-time clock is thus dependent on the frequency generated by the quartz oscillator. However, the frequency generated by the quartz oscillator is susceptible to the effects of the ambient temperature or the manufacturing process, thus resulting in frequency drift. There is usually a −20 ppm and 20 ppm variation rate in the frequency generated by the quartz oscillator. If the frequency generated by the quartz oscillator is not accurate, it results in the inaccuracy of the time counted by the real-time clock. Even though there are many different correction mechanisms to improve the accuracy of the real-time clock, the correction mechanisms are not intuitive and simple.